The present invention relates to a packet-switched communications network which allows message packets to be switched over from one virtual circuit to another in a short period of time in the event of a trouble or traffic overflow.
In a virtual circuit packet-switched communications network, a route is established through the network in response to a call-setup packet sent from a source terminal before interactive communication begins and all participating switching nodes are informed of the connection to route the individual message packets that follow. The route so established is a virtual circuit, or logical channel, which is released at the end of a connection by a call-clearing packet that propagates through the network. In the event of a trouble or heavy traffic in the virtual circuit, the source terminal is informed of the trouble to interrupt the communication and send a call-setup packet again to reestablish a new virtual circuit through the network. Since the call-setup operation involves the erasing of previous routing information and registration of new routing information at all the participating switching nodes and the transmission of a return message, or proceed-to-send packet from the destination terminal to the source terminal, the communication between the source and destination terminals is interrupted for a relatively long period of time.